/*
 * Copyright 2016 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.handler.codec.dns;

import io.netty.util.internal.StringUtil;
import io.netty.util.internal.UnstableApi;

/**
 * An <a href="https://tools.ietf.org/html/rfc6891#section-6.1">OPT RR</a>
 * record.
 *
 * This is used for <a href="https://tools.ietf.org/html/rfc6891#section-6.1.3">
 * Extension Mechanisms for DNS (EDNS(0))</a>.
 */
@UnstableApi
public abstract class AbstractDnsOptPseudoRrRecord extends AbstractDnsRecord
        implements DnsOptPseudoRecord
{

    protected AbstractDnsOptPseudoRrRecord(int maxPayloadSize,
            int extendedRcode, int version)
    {
        super(StringUtil.EMPTY_STRING, DnsRecordType.OPT, maxPayloadSize,
                packIntoLong(extendedRcode, version));
    }

    protected AbstractDnsOptPseudoRrRecord(int maxPayloadSize)
    {
        super(StringUtil.EMPTY_STRING, DnsRecordType.OPT, maxPayloadSize, 0);
    }

    // See https://tools.ietf.org/html/rfc6891#section-6.1.3
    private static long packIntoLong(int val, int val2)
    {
        // We are currently not support DO and Z fields, just use 0.
        return ((val & 0xff) << 24 | (val2 & 0xff) << 16 | (0 & 0xff) << 8
                | 0 & 0xff) & 0xFFFFFFFFL;
    }

    @Override
    public int extendedRcode()
    {
        return (short) (((int) timeToLive() >> 24) & 0xff);
    }

    @Override
    public int version()
    {
        return (short) (((int) timeToLive() >> 16) & 0xff);
    }

    @Override
    public int flags()
    {
        return (short) ((short) timeToLive() & 0xff);
    }

    @Override
    public String toString()
    {
        return toStringBuilder().toString();
    }

    final StringBuilder toStringBuilder()
    {
        return new StringBuilder(64).append(StringUtil.simpleClassName(this))
                .append('(').append("OPT flags:").append(flags())
                .append(" version:").append(version())
                .append(" extendedRecode:").append(extendedRcode())
                .append(" udp:").append(dnsClass()).append(')');
    }
}
